package cn.fuck;

abstract class A {
    public void show() {

    }

    public abstract void fuck();
}

abstract class B extends A {
    // 不用实现任何方法
}

class C extends A {
    @Override
    public void show() {
        System.out.println("C.show()");
    }

    @Override
    public void fuck() {
        System.out.println("C.fuck()");
    }
}

class D extends C {
    @Override
    public void fuck() {
        System.out.println("D.fuck()");
    }
}

public class TestAbstract {
    public static void main(String[] args) {
 /*       A aA = new D();
        aA.fuck();
 */
        Object os = null;
        int[] is = new int[6];
        os = is;
        System.out.println(os);

    }
}
